Circuit breaker



April 17, 1934- w. B. WHITNEY El AL CIRCUIT BREAKER Filed March 4, 19322 Sheets-Sheet l m E/ym/Ps jog/k7 I 4770/?A/EKS April 17, 1934. w. B.WHITNEY Er AL C IRCUIT BREAKER Filed March 4, 1932 2 Sheets-Sheet 2 Fig.Z

a cylinder and current UNITED This invention relates STATE SPATENT-OFFICE CIRCUIT BREAKER Willis Bevan Whitney and Edmund BasilWedmore, London, ish Electrical England, assignors to The Britand AlliedIndustries Research Association, London, England, a British com-Application March 4, 1932, Serial No. 596,853 In Great Britain March 18,1931 14 Claims.

to alternating current electric switches or circuit breakers andparticularly to fluid blast switches in which an arc is formed betweenadjacent electrodes when they 5 are separated at the instant of openingthe switch and is caused to move in a particular direction by theapplication of fluid in motion, the force of which may be utilized toovercome any electromagnetic force which may tend to cause the arc tomove in an opposite direction in such a way as to prevent the switch orcircuit breaker from functioning.

The object of the present invention is to provide a construction whichensures that the elec tromagnetic forces set up are such as to assistthe return of an arc root to a region swept by I the blast, should ittend to wander from that region.

In circuit breakers dealing with large amounts of power, it is generallyprovision that the arc is kept relatively short whilst the current isheavy and this is ensured in designs of the type in advantageous to makequestion by a relatively small separation of the electrodes in the firstinstants when the arc is drawn so that the arc roots are retained withina region scoured by a highly intense blast of fluid. Now, in providingmeans according to this invention to prevent the are being forcedelectromagnetically againstthe fluid stream, it is also arranged thatthere shall be no considerable electromagnetic force tending to extendthe arc in the neighbourhood where it is first formed, or to move theblast away from the the root or roots with region where the fiuid blastwashing the-root or roots is of a given degree of intensity.

When the arc is rooted on the surface of a conductor extending inopposite directions and the current travels in one direction along theconductor, a magnetic field is set up which tends to cause the arc rootto move along the surface towards the part carrying 1:0 current, and weutilize such force for our purpose. If, for example, an arc strikes t heinner surface of a is conveyed from one end,

the current at a particular pointtends to be distributed equally aroundthe cylinder tending to create no internal field but where currentconcentrates towards the arc root, a local field is set up. This effectcan be increased when denarrow segments or strip To ensure, therefore,

that the arc shall be that upon movement of the arc, current from one orother end is increased so as to oppose the mo- 9 tion. This .may beensured by leading current into the conductor at two points on eitherside of the are or by returning one end of the conductor upon itself sothat when the arc travels on to that return portion the direction of theconcen- 5 trated current flow is reversed.

In order that the invention may be clearly understood and readilycarried into efiect, some constructions of gas blast switches in accordance therewith will now be described more fully 7 by way of example withreference to the accompanying drawings, wherein'.-

Figure 1 is a diagrammatic central vertical section of the upper part ofone construction of switch;

Figures 2 and 3 are similar views of alternative constructions;

Figure 4 is an assembly view; and Figure 5 is a central vertical sectionsimilar to Figure 1 showing yet another alternative con- 30 struction;

Figure 6 shows yet a accordance with the invention;

Figure 7 is a cross section on in Figure 6.

In these drawings various constructions in acfurther construction in andthe line VIL-VII cordance with the invention are shown for the upperpart of the switch casing and these con structions may be employed asmodifications of the top part of a switch such as shown and described inour United States Patent application Serial No. 180,204 filed 1st April,1927.

In the construction shown in Figure 1, the usual nozzle contact 1 hasscrewed into its lower edge a turned up part 2 which reaches practicallyto the restricted throat 3 of the contact 1. The current connection 4 isshown in this figure, at the'top of the contact 1 so that when theswitch is opened as shown in the figure, current flows down from thelead-in 4 to the restricted throat 3 and then dlrectly through the arcto the contact pin 5. The latter is shown resilient with its end formedwith a slit 6 to enable it to enter the throat 3 of the rigid outercontact. Under the conditions set forth, the current distribution issuch that there is a slight te==-2ncy to blow the root of the arcdownwards by the magnetic field set up by the current flowing down inthe contact 1. However, any bowing of the arc between the central pin 5and the side wall of the contact 1 may tend to no cause upward movementof the are due to the greater general concentration of current in thecontact pin 5. If, in spite of this, the arc crosses the gap and becomesrooted on the upper edge of the inner lining member 2, the current thenhas to flow from the lead-in 4 to the bottom of the nozzle contact 1andthenup the inner lining 2 to the arc and thence to the contact pin 5.The cur rent flowing up in the inner upturned part 2 has a more vigorousmagnetic action than that in the outer shell of the contact 1 and actsimmediately to blow the are up again into its original position on theinner wall of the contact 1. The action may be made more intense byproviding the inner upturned portion 2 with longitudinal slits,indicated at 2a by the dotted lines, so that when the arc jumps on tothe edge of the member 2, the

' current is confined to one of its segments and almost up to thetherefore has a more concentrated action. Slots or holes as indicated at3a by the dotted lines may also be provided in the lower part oftheouter shell 3 to give access to the back of the parts 2 to provide aninward scouring blast across the upper edges of 2 to prevent the arefrom getting to the back of that part.

In the form of construction illustrated in Figure 2, the nozzle contact1 is made in one piece, secured to the top of the switch casing 7 towhich the pressure gas is supplied. At the throat 3, therefore, there isan internal projecting arcing surface at about the middle height of thecontact 1. The latter has parallel leads-in at 4 and 8 respectively atthe top and bottom of the contact so that the switch current flows fromthe top and from the bottom so as to unite at about the throat 3 and toflow into the arc and thence to the moving central switch pin 5. It willbe seen that if the arc becomes displaced either upwardly or downwardlythere is an unbalanced magnetic force due to the current flowing in thenozzle contact 1 which tends to move the are back to its originalposition. In this case also the member 1 may be formed of a number ofsegments to concentrate current and magnetic action in the region of theare root.

In the form of construction shown in Figure 3, the nozzle contact 1 issubstantially a cylindrical body, but with an inward downwardly-turnedmember 9 screwed into the upper part and formed with the throat 3. Theeffect is improved again if the member 9 is slit in the same way asdescribed for the member 2 in Figure 1. Asillustrated the lead-in 4 isin this case at the baseof the contact 1. If the arc tends to movedownwards and crosses the gap between the bottom edge of the inturnedmember 9 and the inner wall of the lower part of the outer'cylindricalcontact 1, the current has a tendency for blowing the are up from below.The lower part of the memberl may also be slit netic effect and theannular gap between the flanged entrance to the bottom of the member 9and the lower inner wall of the cylinder 1 fitted with a packing ofinsulating material 1a.

It is of course, perfectly feasible to have a noz zle contact withturn-in portions both at the top and bottom. Thus-in Figures 4 and 5 themain body of the contact 1 has a central waist at the throat 3 at whichthe inner moving contact pin 5 makes contact- An internal slit piece 2similar in shape to that shown in Figure 1 is screwed in at the bottomof the contact 1 so as to extend waist and a shorter slit piece 9similar to that shown in Figure 3 is screwed in at the top. The contact1 is rigid at the waist and are first 'moves to produce a concentratedmag' therefore it is desirable, in this case, for the moving contact pin5 to be slit at 6 so as to make satisfactory contact at the waist. Thelead-in connection 4 for the current is at the foot of the nozzlecontact 1. In this case, when the arc lies between the moving contactpin 5 and the throat 3 of the contact 1, the current flowing upwardly inthe outer shell of the contact 1 tends to move it in the direction ofthe fiow of the gas blast. If, however, in spite of this the arc doesstrike-across the gap to the edge of the lower internal piece 2, currentwill flow upwardly in the latter and its magnetic action will be to blowthe arc upwards again into its original position as would also be theaction if it struck the lower part of the member 1, but in this case itwould be weaker unless the lower portion of 1 is slit. 0n the otherhand, if the arc travels upwards and crosses the gap to the edge of theupper internal slit piece 9 current will flow right to the top of thecontact 1 and down the prongs of the piece 9 and the current in thelatter will again blow the are down into its original position. It willbe noted that the member 2 is perforated to allow of the escape of gasinto the annular space surrounding it. Furthermore, the slits betweenthe prongs of the member 9 are filled with strips of soft iron 11meeting in the lower ring 12 in order to cause'the electromagneticaction on the arc root to be intensified. Figure 4 illustrates theassembly of this embodiment, the switch casing constituting apressure-retaining vessel being indicated at 15 and having an inlet pipe16 for the gas which is to produce the blast. The operating mechanismfor the moving switch pin 5 is of the usual kind including a cross bar1'7, a guided operating rod 18 encircled by an operating spring 19, thewhole being mounted on a base or framework 20.

In the construction shown in Figures 6 and 7, the construction of Figure5 is modified by extending the inner it with a waist 3 so that it formsin effect the nozzle contact itself. As it is slit and resilient at thewaist the moving contact pin 5 may be nonresilient. When the arc isstruck in this case, current flows upwardly from the lead-in conductor 4through the -internal piece 2 and the up slightly, then any upward ordownward movement of the arc will vary the path of the current so thatappropriate magnetic restoring forces come into play. Thus, if the arccrosses the gap to the lower edge of the upper internal piece 9 thecurrent will again flow up through the outer shell 1 to the top and thendown through the prongs of the'upper internal piece 9 as in rated toprovide some escape for the hot expanding gases which have passed thearc. It will be noted that the segments of the member 2 are carried bylaminated plates 13 which are carried within a ring 14 screwed in thelower end of the shell 1 so as to increase the yielding action of themember 2 when the contact'pin 5 enters the constricted portion of themember 2.

In any of the forms of construction described above the action may beintensified by providing slit portions of the members with ironstrips'as at 11 and 12 which in Figures 5 and 6, extend along the edgesof the upper internal piece 9. In Figures 5, 6 and '7 iron may be placedbehind the copper electrode rial may be provided between the slit stripsand the outer conducting cylinder. l

or a cylinder of magnetic matethe leading-in conductor may It will beunderstood that the forms of construction shown in Figures 1, 4, 5 and 6are not only suitable for use in cases in which a sudden pressure offluid is applied at the time of arcing, but also in cases in which fluidis stored under pressure in the arcing cylinder for some time before itis required for use in extinguishing the are, as especially in thelatter cases, a valvecan be easily mounted on the top of the outer shellor on an extension pipe from the shell so that owing to the continuousor solid nature of the outer shell, fluid can be retained under pressurein and around the slit parts of the electrode. The same result can beattained with the forms of construction shown in Figures 2 and 3 bymounting them in an outer shell. It will be understood from thedescription given above in regard to the functions of the variousmembers and their configurations that the point of attachment of theleading-in conductor may be altered somewhat, without departing from thescope of the present invention. For example, it is clear from theconfiguration of the current carrying parts in the forms of constructionillustrated in Figures 5, 6 and 7, that the position of the attachmentof be altered to any other point on the shell 1, above that shown in thedrawings, without altering the correct functioning of the members 2 and9.

We claim:-

1. An alternating current circuit breaker comprising in combination acasing, apair of relatively movable electrodes mounted therein, meansfor supplying a blast of fluid to the arcing surfaces of saidelectrodes, and to said electrodes, one of said electrodes being soshaped and having a current connection at such a point that upon a rootof the are formed on opening the circuit breaker becoming displaced fromits normal position in an intermediate region on the surface of thatelectrode in a direction substantially parallel to the direction of flowof the fluid, the eifective direction of flow of current to that areroot is such as to create a magnetic field tending to return said areroot to said intermediate region on the surface of said electrode.

2. An alternating current circuit breaker, comprising in combinationacasing, a fixed electrode mounted therein, a movable electrode mountedto co-operate with said fixed electrode, operating mechanism for saidmoving contact, means for supplying a blast of fluid to the arcingsurfaces of said electrodes and current connections to said electrodes,said fixed electrode being so shaped and a current connection beingattached to it at such a point that upon a root of the are formed onopening the circuit breaker becoming displaced from the normal positionin an intermediate region on the surface of said fixed electrode in adirection substantially parallel to the direction of flow of the fluid,the effective direction of flow of the current into that are root issuch as to set upa magnetic field tending to return said are root tosaid intermediate region on the surface of said nxed electrode.

3. An alternating current circuit breaker, com prising in combination acasing, adjacent relatively movable electrodes mounted therein, meansfor supplying a blast of fluid to the arcing sur faces of saidelectrodes, one of said electrodes being shaped to form a hollowpassageway for the blast fluid and comprising a number of segments heldresiliently together and a current supply conductor connected to saidsegments so that current connections current reaches the arc root fromthe same gen eral direction as the said blast fluid.

4. An alternating current circuit breaker, comprising in combination, acasing, a pair of relatively movable electrodes mounted therein, meansfor supplying a blast of fluid to the arcing surfaces of saidelectrodes; and current connections to said electrodes, the currentconnections to one of said electrodes being arranged to lead currentinto said electrode at points spaced apart in a direction substantiallyparallel to the direction of flow of the fluid, on either side of theare formed on opening the circuit breaker.

5. An alternating current electric circuit breaker, comprising incombination, a casing, a pair of relatively movable electrodes mountedtherein, means for supplying a blast of fluid to the arcing surfaces ofsaid electrodes, and current connections to said electrodes, one of saidelectrodes being shaped to constitute a hollow passageway for said blastof fluid and with a reentrant portion with its edge directed towards theare formed on opening the circuit breaker so that when said are movesbetween the inner wall of said lastmentioned contact and its re-entrantportionthe distribution of current in said re-entrant portion is alteredso as to set up a magnetic force tending to restore the arc to itsoriginal position.

6. An alternating current electric circuit breaker comprising incombination a casing, a hollow electrode mounted therein and formed witha constricted threat, a eo-operating electrode mounted to moverelatively to said hollow electrode so as to make contact with saidhollow electrode at the throat thereof and current connections to saidelectrodes, said hollow electrode being formed with re-entrant portions,one on either side of said throat.

'7; An alternating current electric circuit breaker comprising incombination, a casing, a pair of relatively movable electrodes mountedtherein, means for supplying a blast of fluid to the arcing surfaces ofsaid electrodes, and current connec tions to said electrodes, one ofsaid electrodes being so shaped and having a current connection to it atsuch a point that upon the root of the are formed on opening the circuitbreaker becoming displaced from its normal position in an intermediateregion on the surface of that electrode, the effective direction of flowof current into that are root is such as to create a magnetic fieldtending to return said are root to said intermediate region on thesurface of said electrode in a direction substantially parallel to thedirection of flow of the liquid and said last-mentioned being slit overthe portion aiong which the are root is moved in the general directionin which the arc root is moved so as to concentrate the current flowingto the are when the latter moves on to a part of said electrode betweenthe slits.

8. An alternating current electric circuit breaker comprising incombination a casing, a pair of relatively movable electrodes mountedtherein, means for supplying a blast of fluid to the arcing surfaces ofsaid electrodes and current connections to said electrodes, the currentconnection to one of said electrodes being arranged to lead current tosaid electrode at points spaced apart in a direction substantiallyparallel to the direction of flow of the fluid, on either side of theare formed on opening the circuit breaker, said lastmentioned electrodebeing slit in the general direction in which the arc root is moved overthe portion along which the arc root is moved, in

order to concentrate the current flowing to the are when the lattermoves on to the electrode between the slits.

9. An alternating current circuit breaker comprising in combination, apressure retaining vessel, a hollow electrode mounted on said pressureretaining vessel, a casing surrounding said hollow electrode, means forsupplying a blast of fluid to said hollow electrode, a movable electrodemounted to co-operate with said hollow electrode a current connection tosaid movable electrode and a current connection to such a point in saidhollow electrode that upon a root of the are formed on opening thecircuit breaker becoming displaced along the inner surface of saidhollow electrode from its normal intermediate position on that surface,the eifective direction of flow of current to that are root in saidhollow electrode is such as to create a magnetic field tending to returnsaid are root to said intermediate region on the surface of said hollowelectrode, the walls of said hollow electrode being provided with slitswhich open into said casing.

10. An alternating current circuit breaker comprising in combination, apressure retaining vessel, a pair of relatively movable electrodes onemounted on said pressure retaining vessel, a casing surrounding saidlast-mentioned electrode, means for supplying a blast of fluid to thearcing surfaces of said electrodes and current connections to saidelectrodes, one of said electrodes being so shaped and having itscurrent connection at such a point that upon a root of the are formed onopening the circuit breaker becoming displaced from its normal positionin an intermediate region on the surface of that electrode in adirection substantially parallel to the direction of flow of the fluidand one of said electrodes being formed with slits in the generaldirection in which the arc root is moved over the portion along whichthe arc root is moved so as to concentrate the current flowing to theare when the arc moves on to the part of that electrode between theslits, said slits opening into said casing.

11. An alternating current circuit breaker comprising in combination, acasing, a pair of relatively movable electrodes mounted therein, meansfor supplying a blast of fluid to the arcing surfaces of saidelectrodes, current connections to said electrodes and magnetic materiallocated behind one of said electrodes in order to intensify the actionof said magnetic field, one of said electrodes being so shaped andhaving a current connection at such a point that upon a root of the areformed on opening the circuit breaker becoming displaced from its normalposition in an intermediate region on the surface of that electrode in adirection substantially parallel to the direction of flow of the liquid,the effective direction of flow of current into that are root is such asto create a magnetic field tending to return said are root to saidintermediate region on the surface of said electrode.

' 12. An alternating current circuit breaker comprising in combination acasing, a pair of relatively movable electrodes mounted therein, onebeing formed with slit walls, means for supplying a blast of fluid tothe arcing surface of said slit electrode, current connections to saidelectrodes and magnetic material located along the edges of a slitportion of said last named electrode to intensify the electromagneticaction on the arc root of the current flowing in said electrode, saidslit electrode being shaped to provide a hollow passageway for saidblast fluid.

13. An alternating current circuit breaker comprising in combination acasing, a hollow electrode mounted therein, means for supplying a blastof fluid to said hollow electrode, a co-oper-' ating electrode mountedto move relatively to said hollow electrode a current connection to saidcooperating electrode and a current connection at such a point in saidhollow electrode that upon a root of the are formed on opening thecircuit breaker becoming displaced from its normal intermediate positionon the surface of said hollow electrode the effective direction of flowof the current into that are root is such as to set up a magnetic fieldtending to return said arc rootto the intermediate region on the surfaceof said hollow electrode, the wall of said hollow electrode beingprovided with a plurality of perforations connecting together the spaceson both sides of the said wall to allow of the passage of the blastfluid.

14. An alternating current circuit breaker comprising in combination acasing, a pair of relatively movable electrodes mounted therein, onebeing hollow and having its wall perforated, means for supplying a blastof fluid to the passageway in said hollow electrode and currentconnections to said electrodes, said hollow electrode being so shapedand having a current connection at such a point that upon a root of thearc formed on opening the circuit breaker becoming displaced from itsnormal position in an intermediate region on the surface of thatelectrode, 1 5 the effective direction of flow of current to that areroot is such as to create a magnetic field tending to return said areroot to said inter mediate region on the surface of said electrode.

WILLIS BEVAN WHITNEY. 13 0 EDMUND BASIL WEDMORE.

